The ALPINE-ALMA [CII] survey: The contribution of major mergers to the galaxy mass assembly at z~5

Vol. 653
4. Extragalactic astronomy

The ALPINE-ALMA [CII] survey: The contribution of major mergers to the galaxy mass assembly at z~5

The ALMA ALPINE survey is a recently completed ALMA large program that is providing new valuable insight into the nature of star-forming galaxies up to z=6. In this work, the authors combine the ALMA observations to multi-wavelength data to study the morphology and kinematics of the ALPINE galaxies with the aim of assessing the importance of major mergers in the process of galaxy mass assembly at early cosmological epochs. The obtained constraints reveal the presence of a significant merging activity in the early Universe. The exact contribution to the galaxy mass build-up at these redshifts and through the cosmic epochs is strongly dependent on the assumption of the merger timescale. If a rapidly evolving merger timescale such as TMM ∝ (1+z) ^−2 is assumed, the results agree well with state-of-the-art cosmological simulations, suggesting a considerable role of mergers in the build-up of galaxies at early times.